(1) Field of the Invention
The present invention relates generally to circular knitted fabric and, more particularly, to a pill-resistant knitted fabric and article of apparel having a print-receptive face and good print resolution even after multiple home washings.
(2) Description of the Prior Art
The term circular knitting covers those weft knitting machines having needle beds arranged in circular cylinders and/or dials including latch, bearded and occasionally compound needle machinery. Such machines produce a wide variety of fabric structures, garments, hosiery and other articles and a variety of diameters and machine gauges. Such machines have the needles fixed in a revolving circle with the loop formation and knitting action being achieved by ancillary elements moving yarn and loops along the needle stems producing a fabric tube with the technical face facing backwards. Large diameter circular knitting machines are generally used to produce either fleece or jersey fabrics as well as other fabric constructions. The following discussion is taken generally from Spencer, David J., Knitting Technology, (2d. ed. 1989), which is a general treatment of knitting technology and is hereby incorporated by reference in its entirety.
Knitted fabrics are progressively built up by converting newly fed yarn into new loops in the needle hooks, the needles then draw these new loops head first through the old loops, which have been retained from the previous knitting cycle. The needles at the same time release, cast off or knock-over old loops so that they hang suspended by their heads from the feet of the new loops whose heads are still held in the hooks of the needles. A cohesive structure is thus produced by a combination of the intermeshed loops and the yarn joining those loops together through which it passes.
Knitted loops are arranged in rows and columns roughly equivalent to the warp and weft of woven structures termed "courses" and "wales" respectively. A course is a predominately horizontal row of loops (in an upright fabric) produced by adjacent needles during the same knitting cycle. A wale is a predominantly vertical column of needle loops produced by the same needle knitting at successive knitting cycles and thus intermeshing each new loop through the previous loop.
"Yarn count" indicates the linear density (yarn diameter or fineness) to which that particular yarn has been spun. The choice of yarn count is restricted by the type of knitting machine employed and the knitting construction. The yarn count, in turn, influences the cost, weight, opacity, hand and drape of the resulting knitted structure. In general, staple spun yarns tend to be comparatively more expensive the finer their count, because finer fibers and a more exacting spinning process are necessary in order to prevent the yarn from showing an irregular appearance.
The conventional technique for painting or decorating fabrics, such as Tee shirts, is screen-printing. In a typical screen printing operation, a separate screen is made for each color to be applied. A first screen is brought into registry with the fabric surface and a first color painted thereon. A second, third, and fourth screen, if necessary, each representing different colors, is then brought into registry with the surface and the additional colors painted or brushed thereon through the pattern in the screen.
In the textile industry, the problems associated with screen printing have been overcome, to some extent, by a process known as "heat-transfer printing" in which a carrier consisting usually of paper or aluminum foil is printed with sublimable dyes temporarily affixed to the carrier by the use of binders. The carrier so printed is then laid with the printed side adjacent the fabric to be printed, and is then heated under pressure to a temperature in the range of 160.degree. C. to 220.degree. C. on the unprinted side of the carrier to sublime the dyes onto the fabric.
Heat-transfer printing techniques have been attempted onto a wide variety of sheet-like articles such as wood, metals, glass, ceramics, and certain synthetic resins by providing such articles with a surface layer or coating of a thermoplastic resin which adheres to the surface of the substrate and accepts the sublimable dyes. See e.g., German patent No. DE 2,642,350; French Pat. No. 2,230,794; and British Pat. No.1,517,832. Similarly the surface of the article to be printed may be coated with a thermosetting resin (published European patent application No. 14,901) which receives the dyes. Characteristic of all of the above approaches is that the transfer of the dyes by sublimation onto a thermosetting or thermoplastic resin is effected by means of heat supplied or generated by an external source.
Natural fibers, such as cotton and rayon, do not readily accept or retain sublimable dyes. Because of this shortcoming, polyester/cotton blends dyed in this way exhibit "grin through" since the cotton portion of the fabric remains undyed. In addition, polyester/cotton blends are notorious for "pilling" which further degrades the printed image after a few home washings. While it is generally believed that pilling only occurs with polyester/cotton blends, pilling will also occur in knitted 100% polyester fabrics if staple yarns are used. However, this is not usually observed since polyester staple fibers are seldom used without first being blended with cotton fibers because 100% polyester fabric is uncomfortable to wear against the skin. Consequently, most 100% polyester fabrics that are used for apparel are usually either knitted or woven continuous multi-filament yarns because of the high strength and low cost of these yarns.
Woven 100% synthetic fabric is an ideal substrate for receiving sublimable dyes because of the composition of the yarn and the stability of a woven construction. Unfortunately, the hand, drape, opacity and comfort of a woven 100% polyester fabric are even more unacceptable to the average consumer than the poor appearance of "grin through". As a result, 100% polyester sublimable dyed woven fabrics are usually reserved for banners and other non-apparel uses.
Thus, there remains a need for a new and improved fabric that is print receptive to sublimable dyes like a 100% synthetic fabric and pill-resistant like a continuous multi-filament synthetic fabric while, at the same time, provides the comfort and appearance of a knitted cotton or cotton/polyester stable blend which is suitable for apparel articles, such as Tee shirts.